The General Motors 4L85E (or MN8) 4-speed automatic transmission was produced from 2000 to 2006 and was installed only with the 8.1-liter L18 V8 engine and the 6.5-liter Duramax V8 diesel. This automatic transmission is familiar from the Chevrolet Avalanche, Suburban, Express, and similar GMC models.
Specifications
| Type | automatic transmission |
| Number of gears | 4 |
| Type of drive | rear / all wheel |
| Engine volume, l | up to 8.1 |
| Torque output, Nm | up to 650 |
| Recommended oil | ATF Dexron VI |
| Oil capacity, liter | 12.7 |
| Partial replacement, liter | 6.3 |
| Maintenance | every 80 000 km |
| Gearbox lifespan, km | ~350 000 km |
| Weight, kg | 118 |
Gear ratios GM 4L85E
Using the 2004 Chevrolet Avalanche with an 8.1-liter engine as an example:
| Main | 4.1 |
| 1st | 2.482 |
| 2nd | 1.482 |
| 3rd | 1.000 |
| 4th | 0.750 |
| Reverse | 2.077 |
Using
The transmission was installed on:
- Chevrolet Avalanche 1 (GMT805) in 2001 – 2005;
- Chevrolet Express 1 (GMT600) in 2001 – 2002;
- Chevrolet Silverado HD 1 (GMT880) in 2001 – 2006;
- Chevrolet Suburban 9 (GMT830) in 2000 – 2005;
- GMC Savana 1 (GMT600) in 2001 – 2002;
- GMC Sierra HD 2 (GMT880) in 2001 – 2006;
- GMC Yukon XL 2 (GMT830) in 2000 – 2005.
Disadvantages of the GM 4L85 gearbox
- This is a very durable transmission, and problems only appear at high mileage;
- The majority of complaints here are related to slippage due to worn clutch packs;
- This is usually caused by a drop in transmission oil pressure due to worn bushings;
- The lifespan of the bushings is significantly reduced if the automatic transmission cooling system is not maintained;
- Also, older transmissions are prone to regular oil leaks at the seals.
